1. Field of the Invention
This invention relates generally to the electrical treatment of malignant tumors and neoplasms by applying a voltage to affected tissue. Devices and various adaptations therein are described for use in electrical therapy. For example, a partially implantable device is described wherein one or more leads (a.k.a. wires) containing one or more electrodes are implanted into a patient having a tumor. Coupled to the lead or leads is a generator for supplying power to the electrode or electrodes. A portion of the generator may or may not be implanted into the patient.
2. Discussion of the Related Art
Cancer is one of the major causes of hospitalization and death worldwide. However, many of the therapies applied to cancer treatment are either ineffective or not well-tolerated by patients.
Cancer malignancies result in approximately 6,000,000 deaths worldwide each year. In 1995, 538,000 cancer related deaths were reported in the United States, representing over 23% of the total deaths in the United States. This number has increased since 1970 when 331,000 deaths occurred. The estimated number of new cases in the United States in 1997 was 1,382,000. An astounding 40% of Americans will eventually be stricken with the disease and more than 1 in 5 will die from it. The percentage is increasing at about 1% per year and cancer deaths will soon outstrip deaths from heart disease.
Much of the medical care cost associated with cancer results from hospitalization. In 1994 there were 1,226,000 hospital discharges in the United States related to cancer treatment. The cost of cancer in terms of both human suffering and monetary expenditures is staggering. Effective treatment methods, which result in fewer days of hospital care, are desperately needed.
Primary treatment methods currently used in cancer therapy include surgery, radiation therapy, chemotherapy, hormone therapy and many others including bone marrow replacement, biological response modifiers, gene therapy, and diet. Therapy often consists of combinations of these treatment methods. It is well known that these methods may result in sickness, pain, disfigurement, depression, spread of the cancer, and ineffectiveness. Despite recent announcements of potential pharmaceutical “cures”, which may work well in animals and in humans in certain cases, researchers are cautious in overstating their effectiveness. In the case of radiation treatment, rapid decreases in the size of poorly differentiated tumors after treatment may be experienced; however, shortly thereafter the tumor often experiences re-growth. Unfortunately, following re-growth the tumor is generally more insensitive to future radiation treatment attempts.
The approaches previously described, as well as other prior approaches, are not sufficient to meet the needs of real patients. The present invention addresses the above and other needs.